Quantitative susceptibility mapping has been a useful tool to monitor magnetic properties of the tissues. Conventional QSM uses thick slab volumetric scan to ensure accurate deconvolution of the dipole kernel for susceptibility estimation. The requirement of large volume coverage and appropriate resolution lead to very long scan time, which has limited QSM’s integration in a clinical protocol. After inspecting dipole kernel’s property, the present work hypothesized QSM should still be performed with a thinner slab to reduce scan time. The results suggest that the reconstructed susceptibility from a whole brain and a thin-slab scan is highly correlated with conventional QSM and the scan time can be reduced up to 4 times.